Hydroacoustics for density and biomass estimations in aquaculture ponds

The use of hydroacoustics is currently being studied and developed as a promising non-intrusive methodology to monitor and manage fish stocks in aquaculture farms. The main objective of this study was to develop an acoustic method for the estimation of fish density and biomass in inland aquaculture farms and test the accuracy and precision of the estimates with real data provided by the company. The study was conducted in sea bass (Dicentrarchus labrax) production ponds located in Seville (Southern Spain). A Simrad EK60 echosounder with two split-beam circular transducers operating simultaneously at 200 kHz was used for hydroacoustic surveys. Two different hydroacoustic designs were considered: central trajectories and zigzag trajectories. The accuracy and precision of the estimates were examined in order to select the best sampling design. Due to a non-homogeneous fish distribution in the pond caused by the avoidance behaviour, as a response to the sampling disturbance presented by fish, acoustic density and biomass were corrected by applying sampling theory according to the probability of fish detection. When density and biomass were corrected, the estimates became highly accurate and precise with respect to real data, which confirms that the proposed method is adequate. Similarly, acoustic estimates of fish weight were highly in agreement with real data, due to the use of specific equations developed “in situ” for the study. Although no significant differences were recorded in the density and biomass estimates with regard to the trajectory used (central vs. zigzag), it was observed that the most accurate agreement and precision were always obtained in central trajectories. Therefore, central design is proposed as the most appropriate design for hydroacoustic measurements in inland ponds. The results obtained in this study provide estimates of density and biomass that accurately match the real data, supporting the use of hydroacoustics as a potentially valid tool to manage inland aquaculture farms

Testing of new sampling methods and estimation of size structure of sea bass (Dicentrarchus labrax) in aquaculture farms using horizontal hydroacoustics

In aquaculture, monitoring fish size and density is fundamental to improve management and profitability of fish farms. The aim of this study is to test whether horizontally aimed 200-kHz transducers are adequate to obtain fish size structure in open-sea cages in order to apply horizontal hydroacoustics as a non-intrusive and innovative technique in sea bass (Dicentrarchus labrax) farming. Several sampling strategies have been tested by placing the transducer in two different positions: outside the cage and inside the cage. In addition, two sampling approaches have been implemented: placing the transducer at a fixed position or moving it vertically. The results show that horizontal hydroacoustics is a useful technique for monitoring size distribution of sea bass in farming cages. The most adequate sampling method consists of using a vertically moving transducer positioned outside the cage, since it exhibits the narrowest size distributions with the lowest variance estimates, which matches the data provided by fish farmers

El uso de ecuaciones específicas de conversión TS-Talla para la estima de la biomasa de peces en balsas de acuicultura someras mediante métodos acústicos

La acuicultura es un sector con demanda creciente en nuestro país y se encuentra en una etapa donde los procesos de producción y comercialización están consolidados. Actualmente, las empresas acuícolas buscan la mejora en la optimización de gastos y el control de la trazabilidad del producto. Para mejorar estos parámetros, es fundamental tener un control exhaustivo sobre el número de peces que se crían en las balsas de cultivo y la biomasa de estas. En primer lugar, para ajustar la dosis de pienso (gasto más relevante en la producción) y en segundo lugar, para mejorar la trazabilidad y el control de la producción final. La hidroacústica ha demostrado ser una técnica eficaz para la determinación de densidad y biomasa de peces, tanto en sistemas de agua dulce como salada. Con este método no intrusivo, se pretende mejorar la fiabilidad de las estimas de densidad y biomasa y reducir el estrés que provocan a los peces los muestreos convencionales. Este trabajo tiene como objetivo la aplicación de esta técnica para la estima de biomasa de peces en balsas de doradas (Sparusaurata) y lubinas (Dicentrarchuslabrax) en esteros. Para ello, se han elaborado ecuaciones que relacionan el TS (dB), cantidad de sonido que devuelve el pez, con la longitud (mm) de los peces, validándose la eficiencia del uso específico de dichas ecuaciones para la estima de la biomasa de peces en sistemas someros

Impact of the first wave of the SARS-CoV-2 pandemic on the outcome of neurosurgical patients: A nationwide study in Spain

Objective To assess the effect of the first wave of the SARS-CoV-2 pandemic on the outcome of neurosurgical patients in Spain. Settings The initial flood of COVID-19 patients overwhelmed an unprepared healthcare system. Different measures were taken to deal with this overburden. The effect of these measures on neurosurgical patients, as well as the effect of COVID-19 itself, has not been thoroughly studied. Participants This was a multicentre, nationwide, observational retrospective study of patients who underwent any neurosurgical operation from March to July 2020. Interventions An exploratory factorial analysis was performed to select the most relevant variables of the sample. Primary and secondary outcome measures Univariate and multivariate analyses were performed to identify independent predictors of mortality and postoperative SARS-CoV-2 infection. Results Sixteen hospitals registered 1677 operated patients. The overall mortality was 6.4%, and 2.9% (44 patients) suffered a perioperative SARS-CoV-2 infection. Of those infections, 24 were diagnosed postoperatively. Age (OR 1.05), perioperative SARS-CoV-2 infection (OR 4.7), community COVID-19 incidence (cases/10 5 people/week) (OR 1.006), postoperative neurological worsening (OR 5.9), postoperative need for airway support (OR 5.38), ASA grade =3 (OR 2.5) and preoperative GCS 3-8 (OR 2.82) were independently associated with mortality. For SARS-CoV-2 postoperative infection, screening swab test <72 hours preoperatively (OR 0.76), community COVID-19 incidence (cases/10 5 people/week) (OR 1.011), preoperative cognitive impairment (OR 2.784), postoperative sepsis (OR 3.807) and an absence of postoperative complications (OR 0.188) were independently associated. Conclusions Perioperative SARS-CoV-2 infection in neurosurgical patients was associated with an increase in mortality by almost fivefold. Community COVID-19 incidence (cases/10 5 people/week) was a statistically independent predictor of mortality. Trial registration number CEIM 20/217

USO DE IMÁGENES DE DRONES PARA EL ANÁLISIS DE LA INFRAESTRUCTURA DE LA MOVILIDAD URBANA PEATONAL | ACTAS - Jornadas de Investigación

En muchas áreas urbanas y metropolitanas coexisten diferentes tipos de diseños de infraestructura para la movilidad peatonal, pero en algunos casos el espacio público no posee o no responde adecuadamente a la debida canalización de los flujos peatonales. Por otra parte las imágenes capturadas en altura con tecnología de drones, por su opción de amplia vista aérea del tipo bird eye, capacidad de observación en alta resolución espacial, flexibilidad de manejo y monitoreo en tiempo real, pueden contribuir a la interpretación y construcción de interesantes alternativas de diagnóstico en sectores de la red vial urbana con niveles de conflictividad y exposición de riesgo tanto para peatones como conductores. La utilización de estos vehículos aéreos, en comparativa con metodologías tradicionales de relevamiento de información y observación terrestres, abre interesantes oportunidades para monitorear aspectos estáticos y dinámicos sobre parámetros de diseño de la movilidad peatonal como así también su interrelación con la movilidad motorizada. La investigación se apoya en un caso de estudio de la Ciudad de Buenos Aires mediante un análisis de imágenes capturadas desde un dron. Con la ayuda de técnicas basadas en Inteligencia artificial, se automatizará la información provista por las imágenes respecto de conductas y patrones de los desplazamientos peatonales con la interfaz vial en sendas. Asimismo se analizarán aspectos de diseños urbanos y recomendaciones para mejoras de infraestructura urbana que respondan a un paradigma de movilidad sustentable segura. Esta ponencia pretende dar continuidad de las investigaciones que serán llevadas adelante en el UBACYT 20020170100744BA “Nuevas metodologías para el análisis de corredores metropolitanos: aplicación de la tecnología satelital a la gestión de la movilidad urbana y del ordenamiento territorial (FASE III)”, permitiendo al CETAM lograr una mejor comprensión de la dinámica de circulación peatonal y criterios para la adopción de buenas prácticas en movilidad urbana sustentable y segura, hacia las cuales se orientan los hallazgos de esta investigación

Patients awaiting surgery for neurosurgical diseases during the first wave of the COVID-19 pandemic in Spain: a multicentre cohort study.

The large number of infected patients requiring mechanical ventilation has led to the postponement of scheduled neurosurgical procedures during the first wave of the COVID-19 pandemic. The aims of this study were to investigate the factors that influence the decision to postpone scheduled neurosurgical procedures and to evaluate the effect of the restriction in scheduled surgery adopted to deal with the first outbreak of the COVID-19 pandemic in Spain on the outcome of patients awaiting surgery. This was an observational retrospective study. A tertiary-level multicentre study of neurosurgery activity between 1 March and 30 June 2020. A total of 680 patients awaiting any scheduled neurosurgical procedure were enrolled. 470 patients (69.1%) were awaiting surgery because of spine degenerative disease, 86 patients (12.6%) due to functional disorders, 58 patients (8.5%) due to brain or spine tumours, 25 patients (3.7%) due to cerebrospinal fluid (CSF) disorders and 17 patients (2.5%) due to cerebrovascular disease. The primary outcome was mortality due to any reason and any deterioration of the specific neurosurgical condition. Second, we analysed the rate of confirmed SARS-CoV-2 infection. More than one-quarter of patients experienced clinical or radiological deterioration. The rate of worsening was higher among patients with functional (39.5%) or CSF disorders (40%). Two patients died (0.4%) during the waiting period, both because of a concurrent disease. We performed a multivariate logistic regression analysis to determine independent covariates associated with maintaining the surgical indication. We found that community SARS-CoV-2 incidence (OR=1.011, p Patients awaiting neurosurgery experienced significant collateral damage even when they were considered for scheduled procedures